You can set a Reserve Price for items of type LOT and with purchase option of NONE, MAKE_OFFER or BUY_NOW.
When a user places a bid on one of these items and it does not reach the reserve, a progress bar will appear, as follows:
There is no indication of exactly what the reserve price is. As the bids increase, this is reflected in the "current bid" indicator and the bar will fill up until the reserve is reached:
Note: A logged out, non-registered or non-bidding user is not able to see the reserve progress bar, but will be able to see the current bid, as follows. Only the bidding user can see the current reserve progress:
When the reserve is met, bidding commences as normal. This can be seen below as the message to the user has now changed to "Your bid is currently highest":